john banks

Dell 1520 wireless card with latest drivers from Dell website (which improved from 8 times to 4 times slower with security) on a 1st gen Core i7 laptop Win 7 64 bit has a throughput at about 25 megabytes per second with no security and about 6 megabytes per second with WPA2 or WPA.

Wireless repeater is a new Western Digital Mynet N900. Updated firmware makes no difference.

Plugging in the laptop the throughput is over 100 megabytes per second.

The channel width is 40MHz with nothing else on that channel.

Connection speed is 300Mbps. Tried fiddling with all the settings I can which is why I discovered that disabling security helps.

Using 2.4Ghz with 20MHz channel is about 10 megabytes per second.

I don't have any other 5GHz devices to test yet.

Suggestions? I live in the sticks but still don't want an unsecured network.

Whilst I am here, only channel choices are 36, 40, 44, 48, so I can only have two 300Mbps wide non-overlapping channels covering adjacent wifi zones. It is only really me congesting the wifi but stone walls mean I have a five wireless access points now.

tony de wonderful

Don't you mean megabits?

JDM_333

I've got a Cisco Aironet 1252AG (802.11N) at home with both 5ghz and 2.4ghz SSIDs setup and a Dell laptop - let me test and compare when I get home, interested to see the difference!

What are you copying as a test and ill do the same?

john banks

Yes I mean megabytes.

I am copying a approx 475MB single file as a test. Wired this is about 5 seconds, about 20 with unsecured 5GHz, great! Source and destination are SATA 3 7200 RPM drives.

I found some Aztec AV500 gigabit switches just used as switches were overheating with 4 gigabit connections, I had their home plug function turned off. Now fixed with new wired routers and all is well except the 5GHz speed when security is enabled.

hodgy0_2

Why is this a surprise

Encryption puts a large overhead on the "perceived" throughput

Use MAC address filtering

john banks

Not secure though? The same encryption on 2.4GHz makes no obvious difference. Adding the same encryption to 5GHz quarters the speed to half that of 2.4GHz. That doesn't seem right, wondering if due to the wireless card, but my friend google doesn't recognise it.

hodgy0_2

well, how secure do you need it

all ecommerce traffic is over SSL anyway

i suspect you have more chance of someone breaking into you house than MAC address spoofing your wireless connection

JuergenG

It seems that there was a manufacturing problem with the WB N900 causing the 5GHz signal being a lot weaker than the 2,4GHz one. See this article for reference. This could cause many retransmits over the 5GHz band also meaning multiple encryption passes for the same data. Combine this with maybe a slower processing unit and your data rate drops immediately. You could test this with something like inSSIDer, Vistumbler/NetStumbler or Kismet. Especially the SNR readings from Kismet could be of interest.
Other reviews seem to indicate that your router (I think you meant that instead of repeater) is a bit sensitive to crosstalk. See the article here for reference. Other than that, your numbers seem to be even a bit above the average found in various reviews of the router (e.g. here).
Is there a specific reason limiting you to the 5GHz band? Just because you mentioned, that you're living in a uncrowded area and the router also supports channel bonding in the 2,4GHz band.
Also I would not suggest disabling security. Using a MAC filter is basically no security, since spoofing that address of a connected client is a 2 second job on basically every OS. At least here in Germany you easily can get sued, if someone is using your unsecured wireless for illegal activities (secured would mean "uses encryption to prevent access" i.e. WEP and WPA(2) ).
Hope this helps.

john banks

I cannot channel bond my 2.4 GHz band because of congestion from my own routers (all except one have DHCP turned off or are set to repeater mode which does the equivalent if available). As I move through the house devices roam on the same SSID and security but different channels. I have them spread apart enough not to cause dead spots, but they are close enough that sometimes they can see each other and this seems to turn off their channel bonding or make the performance slower than 20MHz during previous testing but will repeat with the Western Digital stuff.

Thanks for the links. I also bought an N750 at the same time, initial test with that was also very slow in 5GHz, will investigate more.

john banks

I tried 2.4 GHz channel bonding again and on a new Dell tablet that will do it, it does file transfers at 20 megabytes per second, but the router won't keep the channels bonded for more than a few minutes before dropping them. The Dell laptop with the 1520 wireless card has a dramatic reduction to less than 1 megabyte per second on the same network even though it shows 300Mbps connection speed.

So the odd thing is the 1520 card doesn't do well with channel bonding and WPA2 on 2.4GHz or 5GHz. I haven't been able to test 2.4GHz with channel bonding and no security as the router keeps narrowing the 40MHz channel to 20MHz.

Will see if Broadcom rather than Dell drivers work better on the 1520.

hodgy0_2

Surely someone sitting in a car, in the middle of nowhere, with a laptop, netstumbler, and a massive hard on, as he furiously w4nks to p0rn downloaded on John,s wifi would raise some sort of Suspicion

Maybe not, we live in strange times

john banks

Broadcom drivers don't help. Running LANtest, the read is slow (30-40Mbps) and the write is fast (150Mbps). Only with channel bonding and WPA2 though. What is more weird is that using another computer on the network to write a file to the one running channel bonding and WPA2 is fast.

Apart from the weirdness of networking what does this tell us? Putting the time into this because I'll run this setup for years if it works.

Definitely a bit strange hodgy0_2, but it just seems bad to have bad security to me which is why I persist. There are some caravan sites not too far away, and a bit of free **** would probably keep them quiet.

tony de wonderful

Could be next door lol. I once exploited an open wi-fi access point near me for over a year. Someone must have forgot to set a password.

hodgy0_2

The the concept of bad security is a bit strange, no such thing, just levels of security

If someone wants to "get" you they will

Obviously I don't know your circumstance, but I doubt they require the levels you are taking things to that's all

hodgy0_2

Agreed, but John has said he lives in a remote location

john banks

There is a neighbour though and I can see their single 2.4GHz secured network.

tony de wonderful

The groundsman's cottage?

john banks

No, the farmhouse. I'm in the cow shed.

JuergenG

Besides the security things - which are personal choice of course - there are multiple things going on here. Didn't know about the multiple access points and repeaters in the setup.
Just to be sure about the technical terms and with how many different devices we are dealing here: from my understanding, access points (APs) with a disabled DHCP are used for the Extended Service Set mode, so they normally all get connected via a wired link to a local network (where the DHCP sits). They can have different channels. Repeaters (be it WDS for WEP/WPA or Universal Repeaters for WEP/WPA/WPA2) usually sit on the same channel as the main AP and basically cut your data rate in half.
One thing to consider here is, that if you are using channel bonding, you are using wireless N features. This has the impact, that there is only the choice between no security and WPA2(AES). If there is the rare option to select WPA (which basically means TKIP instead of AES), most of the time data rates are limited to wireless G speeds (54Mbps, or about 20-22Mbps net).
Couldn't think of a exact scenario at the moment, that would explain this read/write behavior to 100%. But the write speed is actually very close to the maximum net throughput of a 300Mbps link (40MHz, 2 spatial multiplexed streams). Rule of thumb is, that net throughput is half of the link speed. The read however looks more like a 20MHz 2 stream connection with a bit of collision. Could very well be a hidden/exposed terminal problem coming from the request to send/clear to send (RTS/CTS) signaling used for WiFi as one form of CSMA/CA. So it's a location thing of all wireless devices involved in the transmission. To rule out basic compatibility issues, you would have to disable all the other "wireless" devices in the area (routers, wireless clients, bluetooth, DECT phones, microwaves...) and test the wireless card just against the WD router which is a lot of effort for sure...
It might also be of interest, that smaller devices like smartphones or tablets do not always support spacial multiplexed streams just because this technique needs a certain spacial distance between the antennas. So although some state N-standard compatibility, you might be looking at max link speeds of 150Mbps.
Also the N standard describes, that if channel bonding does cause interferrence with other radios on the extended channel, that the extended channel is dropped to reduce congestion. If you have access points running on the recommended channels 1,6,11 they can interfere with the bonding. E.g. if your channel bonded router/AP is running on channel 1 (or 3, depends on notation) it will use channel 5 (1+4) as the next 20MHz chunk. Channel 5 itself again blocks 2 channels up and down so you basically end up blocking channel 1-7 with the bonding. So the channel 6 AP will interfere and most likely slow your connection. Also legacy G standard devices can cause a decrease in performance, since only the first channel (1 in the example) is used for transmissions.

Dell released a 1530 version of that mini wireless card which included some fixes... Unfortunately they did not mention what these fixes were so I think it's not much of a use to you.


Still all this does not solve the 5GHz problems which is a shame, sorry about that... But maybe this gives you some pointers in the right direction.

john banks

Thanks. The routers are all wired with Cat 6 and although my present devices don't have LEDs to tell me the link speeds, the file copy speeds suggest they are all running gigabit.

The Broadcom drivers were no different.

I did manage a test in 2.4GHz with 40MHz width. With the Dell 1520 card, it had a very slow read and a fast write when WPA2 was used, and both read and write were fast when no security was used. With another computer then both read and write were fast with WPA2 or no security.

I have ordered a 6235 card for my XPS18 which will keep the Bluetooth and will allow 5GHz. It may also get tested instead of the 1520 as it does seem to be something to do with the 1520, channel bonding and security. I will report back.

I was thinking more about the security and I could not face leaving it unsecured as it seems reckless with my data which is sensitive in parts and not trivial to my personal and professional/business interests. I am not the type to leave my front door unlocked all the time (it would void my insurance anyway), although my neighbours do without trouble. If I worry about the security even though there is a higher risk of other nastier things happening that don't worry me, then I may be illogical but I will still sleep at night.

john banks

The 6235 on the XPS18 is working a treat in 5GHz with WPA2, file copy speeds of 24 megabytes per second. Might get another to replace the 1520.

hodgy0_2

Glad you go it sorted

So was it a NIC card / driver issues in the end

john banks

Think so.